Found this on Nat Geo about the photograph:
Best known for his development of electromagnetic theory, Scottish physicist James Clerk Maxwell dabbled in color theory throughout his life, eventually producing the first color photograph in 1861. Maxwell created the image of the tartan ribbon shown here by photographing it three times through red, blue, and yellow filters, then recombining the images into one color composite.
Photograph by James Clerk Maxwell
Apparently tartan ribbon is just plaid ribbon.
They are technically distinct. Tartans refer to specific crisscrossed patterns associated with Scottish heritage, whereas plaid is the generic term for that kind of crisscrossed pattern.
James Clerk Maxwell did this, invented color photography. On top of defining the electromagnetic force. What a mad lad indeed!
Imagine the Edinburgh nightlife during Maxwell's time, a hotbed of some of the world's scientific, intellectual elite, and from what I've heard it was a party town. Pubs, taverns and private clubs, Scotch and cigar smoke in the air, perhaps? Something for every occasion, from the rowdy drunken singalongs to the tophat-and-white-gloves society.